Potential therapeutic application of adult stem cells in acute respiratory distress syndrome.

Acute respiratory distress syndrome (ARDS) remains a poor prognosis in spite of the recent development of new therapeutic strategies. Cell-based therapy with stem cells has been considered as a promising way for the treatment of vital organ damage. Putative endogenous stem cells have been shown to be located within the adult lung in the basal layer of the upper airways, within or near pulmonary neuroendocrine cell rests, at the bronchoalveolar junction, as well as within the alveolar epithelium. These stem cells are hypothesized to be the source of lung regeneration and repair. But this mechanism seems to be insufficient after lung injury. There is increasing excitement over the last few years with the suggestion that exogenous stem cells may offer new treatment options for ARDS. Exogenous stem cells have the ability to differentiate and function as both airway and lung parenchymal epithelial cells in both in vitro and increasingly in vivo experiments. However, there is great controversy concerning the repair effect of adult stem cells in lung injury. This review evaluates the advances in endogenous respiratory stem cells, and assesses the evidence for the use of stem cells in the repair of lung injury.